Some mobile devices have turn-by-turn navigation functions. In turn-by-turn navigation, a device can present audio or visual instructions on where to make a next turn and to which direction. Typically, the device relies on accurate location information to avoid providing wrong instructions or providing the instructions too early or too late. In an outdoors environment, the device can use global navigation satellite system (GNSS) signals and street maps to provide turn-by-turn navigation instructions.
Indoor environments, in contrast, may present challenges to turn-by-turn navigation. GNSS signals may be weak or unavailable indoors, resulting in inaccurate location fixes. Features of the indoor environment (e.g., hallways and doors) may be small compared to achievable location accuracy. Accordingly, even when a device has a map of an indoor space, indoor turn-by-turn navigation may be impractical.